Improving the power efficiency of electrical products is receiving an increasing amount of attention both for consumer goods and professional goods. Telecommunications operators are beginning to specify minimum power efficiency for the products they buy and Standards bodies for telecommunications are introducing features to improve power efficiency. As yet, telecommunications transmission products have not been effectively addressed and many of them consume the same amount of power irrespective of the amount of traffic they are carrying. For example, in packet networks transponders make up the bulk of the power consumption requirements and use the same power regardless of whether the optical channel payload unit (OPU) content comprises empty or filled packets. Burst mode transmission has been proposed to reduce power consumption when little traffic is to be carried by turning off the transmitter between bursts. However this requires additional overhead in order to provide clock and burst synchronisation. In addition, burst mode transmission is incompatible with most installed wavelength division multiplexed (WDM) communications network infrastructure, that has been designed for continuous transmission. For example, Erbium doped fibre amplifiers and power monitors used in the optical transport network are generally unsuitable to carry burst mode transmission.